The present invention relates to a fuel injection valve used in an internal combustion engine and, more particularly, to a fuel injection valve having a plurality of fuel injection ports and capable of injecting swirling jets of fuel from the fuel injection ports and thereby improving the pulverizing performance.
A fuel injection valve described in JP-A-2003-336562 is known as a conventional art for promoting pulverization of fuel injected from a plurality of fuel injection ports by using swirling flows.
This fuel injection valve has a valve seat member in which a downstream end of a valve seat cooperating with a valve element is opened in a front end surface, and an injector plate joined to the front end surface of the valve seat member. Between the valve seat member and the injector plate, lateral passages and swirl chambers are formed, wherein the lateral passages communicate with the downstream end of the valve seat, and wherein downstream ends of the lateral passages are opened to the swirl chambers along tangential directions. Fuel injection ports through which fuel caused to swirl in the swirl chambers is injected are formed as holes in the injector plate. Each fuel injection port is disposed offset from a center of the swirl chamber to the upstream end side of the lateral passage by a predetermined distance.
In this fuel injection valve, the radius of curvature of an inner peripheral surface of each swirl chamber is reduced from the upstream side toward the downstream side in a direction along the inner peripheral surface of the swirl chamber. That is, the curvature is increased from the upstream side toward the downstream side in the direction along the inner peripheral surface of the swirl chamber. Also, the inner peripheral surface of the swirl chamber is formed along an involute curve having a base circle in the swirl chamber.
With this arrangement, pulverization of fuel from each fuel injection port can be effectively promoted.
On the other hand, a fuel injection valve described in JP-A-2008-280981 is known as a conventional art for obtaining high-dispersion sprays by using swirling force.
This fuel injection valve has an orifice plate having a plurality of fuel injection ports through which fuel is injected. From the fuel injection ports, curved sprays having swirling force are injected. The fuel injection ports are disposed close to each other to cause the curved sprays collide against each other so that pulverization is promoted.